The use of removable plugs to prevent access to the line terminals of industrial-rated circuit breakers is described in U.S. Pat. No. 4,754,247 wherein the removable plugs are inserted in the circuit breaker cover within the access holes to the line terminals. The plugs are removed when connecting the circuit breakers within an electrical distribution circuit and are later replaced to prevent accidental contact with the energized line terminals.
When a compact current limiting circuit breaker, such as that described within U.S. Pat. No. 4,963,849 entitled "Compact Current Limiting Circuit Breaker" is used within an industrial power distribution circuit, intense arc gases are generated during overcurrent interruption. During the existence of the arc, high temperature gases are generated which must exit from the line side of the circuit breaker enclosure in order to prevent the circuit breaker enclosure from becoming over-stressed. During the arc occurrence, some means must usually be employed to prevent the ionized gases from contacting the associated grounded enclosure to thereby prevent the occurrence of a so-called "line-to-ground" fault. Further means must be employed to prevent the arc gases exiting from one line terminal compartment from contacting a line terminal connector within an adjacent line terminal compartment to prevent a so-called "phase-to-phase" fault.
U.S. Pat. No. 4,639,564 describes one such means integrally-formed within the circuit breaker cover to prevent the arc gases from causing electrical breakdown between a terminal and a proximate conductor.
U.S. Pat. No. 4,928,080 describes a line terminal plug that controls the flow of the arc exhaust gases and prevents access to the line terminal lugs. To connect and disconnect the line terminal lugs within the electric power distribution system, the line terminal plugs must first be removed and then later reinserted within the circuit breaker cover.
This invention accordingly provides means for providing access to the line terminals for connecting and disconnecting the line terminals while simultaneously controlling the egress of arc gases from the circuit breaker enclosure.